There are many situations where it is desirable to have a portable telephone system which is independent of the public telephone lines. In a hostage negotiation or barricade situation it is imperative to isolate the perpetrator and keep him from being able to call out. It is also important to control the incoming calls. This isolation and control is best located at the site of the hostage-taking or barricade directly in the hands of police authorities. A portable, self-powered telephone system which can provide communication with the perpetrator of a hostage or barricade situation and can achieve isolation and control of the perpetrator's phone calls is therefore very valuable to public authorities. Other situations in which such a system would be useful would be, for example, in witness/dignitary protection, in bomb disposal squad communication without RF interference, and in disasters where telephones are disabled by fires, explosions and natural disasters.